Spatial Interaction Models and Sudden Cascade Effects in Population Behavior

It has been observed many times that a sudden shift appears in the preferences of a population. This could be political alignments, or acquiescence to corruption, or even a change in popularly held economic beliefs. All of a sudden, a large fraction of the population shifts in their particular belief system and its associated behavior. This behavior change appears unexpected, given that the underlying preference parameters of the population usually shift slowly. By modeling the population spatial interaction using the Granovetter threshold model and global corruption data, the author shows that this sudden cascade behavior is actually more likely to be seen and that slow shifts are unlikely to happen. This article explores how people affecting each other in their local network can have long-range spatial interaction effects that lead to sudden changes in the overall population’s behavior. This has implications for understanding and anticipating large-scale social change across political, cultural, and economic domains.